Tracheal Sounds Accurately Detect Apnea In Patients Recovering From Anesthesia

Objective: The most common complication in the post anesthesia care unit is respiratory complications,typical of which is apnea.Apneas that if it's not discovered and corrected quickly,which can lead to severe hypoxia,bradycardia,or even cardiac arrest.Therefore,it is important to monitor the apnea in the post anesthesia care unit.At present,the methods of respiratory monitoring commonly used in clinical practice still have some defects in accuracy and real time.The purpose of this experiment was to investigate the feasibility of using a human neck tracheal sounds in the post anesthesia care unit to detect apnea in patients undergoing anesthesia recovery,so as to achieve accurate detection and recognition of apnea.Methods: 1.The tracheal sounds signals and the nasal airflow pressure signals were collected for the analysis of the patients in the post anesthesia care unit.The tracheal sounds characteristic signal design algorithm was used to detect the apnea.The nasal flow pressure signal is treated as a reference signal to reflect the patient's respiratory condition.The detection of apnea by tracheal sounds is compared with that of reference signals.Sensitivity,specificity,positive likelihood ratios and negative likelihood ratios were calculated.2.The tracheal sounds signals and external noise signals of healthy volunteers were collected with and without noise,the nasal flow pressure signal was used as a reference signal to reflect the respiratory status of patients.We use adaptive filtering technology to process the collected neck tracheal sounds signals and external noise signals,improve the quality of tracheal sounds acquisition,and compare the detection of apnea results of use tracheal sounds before and after adaptive filtering.Results: 1.The tracheal sounds and nasal flow pressure signals of 121 patients in the post anesthesia care unit were collected and the total monitoring time was 52.6 hrs.34 of the patients had 236 apnea with a total duration of 122.2 minutes.The sensitivity of tracheal sounds detection of apnea was 92%,the specificity was 98%,the positive likelihood ratios was 46,and the negative likelihood ratios was 0.08.2.Data of 46 healthy subjects were collected.There were 499 apnea in quiet environment and 492 apnea in noisy environment.The total duration was 26.5 hours.In the quiet environment,the adaptive filtering technology is applied to deal with the tracheal sounds,so that the sensitivity of the tracheal sounds apnea detection is changed from 97.2% to 98.2%,and the specificity is changed from 99.9% to 99.8%.In noisy environment,the adaptive filtering technology is applied to deal with tracheal sounds,making the sensitivity of tracheal sound apnea detection from 81.1% to 91.5%,and the specificity from 95.9% to 96.6%.Conclusion: Tracheal sounds can be used to accurately detect patients apnea in the post anesthesia care unit,not only can reduce the harm to patients with respiratory complications,also has an important significance in reducing the work pressure of medical staff,reduce errors and improve medical security.The adaptive filtering technique can effectively improve the quality of the collection of tracheal sounds signals,thus enhancing the sensitivity and specificity of the apnea detection.